1. Field of the Invention
This invention relates to a traveling bag for carrying temperature-sensitive medications such as insulin, and more particularly to a bag which includes a sensor to monitor the interior temperature which is continuously displayed on an exterior gauge.
2. Description of the Related Art
Diabetics and other persons under medical treatment often are required to take injections to forestall unconsciousness or other ill effects. In many cases the medication must be stored at a temperature considerably lower than the ambient temperature. Patients who remain at home or whose job responsibilities never require them to travel can store their medications in a refrigerator. For business people who must travel and vacationers, the ability to travel freely often is greatly constrained because they must always keep medications with them to allow proper time-phased administration of dosage, and can find themselves unavoidably in a hot climate where a medication can be spoiled by overheating. Insulin is particularly susceptible to deterioration and must be maintained at a temperature between 38.degree. F. and 84.degree. F. Other commonly prescribed medications which are temperature unstable are glyceryltrinitrate, benzodiazepines, prochlorperazine, penicillin, pseudoephedrine, promethazine, prednisolone and captopril.
Bags, cases, coolers and pouches for carrying temperature-sensitive medications, particularly insulin, are described in the related art. U.S. Pat. No. 3,148,515 to R. Jentis et al. discloses an insulin travel kit which includes a bimetallic thermostatic element which controls the discharge of liquid refrigerant from a supply bottle into a heat-exchange coil encircling an insulin bottle wherein the refrigerant is evaporated and from which the resultant gas is discharged into the air. The element is contiguous to the coil. Whenever the temperature measured by the element rises above 40.degree. F., the element curls so as press against the hook of a valve stem, rocking a throttle valve member on its seat until refrigerant is released. When the temperature goes back down to 40.degree. F., the element bends in the reverse direction, permitting the throttle valve member to rock back into closed position. These reverse temperature regulating actions occur repeatedly and automatically.
U.S. Pat. No. 4,250,998 to F. Taylor discloses a travel kit having thermally insulated peripheral and bottom walls determining a cavity sized to receive an inner container. The container and a top lid determine an annular chamber which is filled almost full with water which is then frozen into an annular ring of ice surrounding a compartment in the container upper portion. An insulin bottle within the compartment remains cold because, in addition to its being thermally insulated, as the frozen water melts, ice remains afloat and in thermal contact with the compartment outer wall.
U.S. Pat. No. 4,322,954 to L. M. Sheehan et al. discloses a portable cooler consisting largely of insulative foam material for transporting medications which must be kept at lower than ambient temperature. The cooler includes an ice compartment and a medicine compartment. Each compartment contains a metallic heat sink. The sinks are thermally and mechanically connected by a heat tube, i.e., a sealed container containing a substance having a well-defined boiling point which may depend on the pressure within the tube. When the tube lower end is colder than the boiling point, the substance collects at the lower end in liquid form. If the temperature at the lower end thereafter increases to the boiling point, the substance begins to boil and heat is absorbed as some of the substance is converted into a gas. The gas carries the heat to the tube upper end where the heat is released as the gas condenses back into a liquid which trickles down the walls of the tube to collect again at the lower end. The tube thus provides a one-way path for heat transfer from the medicine compartment to the ice compartment, and acts as a thermostat to limit the temperature of the medicine compartment.
U.S. Pat. No. 4,343,158 to J. H. Campbell discloses a flexible, insulated open-mouth pouch having a pair of opposed walls joined to form a bottom, and a water-repellent liner. Each wall has a layer of insulating material sandwiched between two outer and inner wall layers. The liner includes front and rear partitions bounding a central pocket for holding a refrigerant. The front partition forms together with the liner front wall a compartment for holding a vial of insulin, and the rear partition forms together with the liner rear wall a compartment for holding a hypodermic syringe.
U.S. Pat. No. 4,429,793 to E. G. Ehmann discloses a pocket-sized traveling case for storing insulin. The case includes thermally insulated front and back covers pivotally attached to each other by a central binder, and is opened and closed by a zipper. The inside of the back cover is provided with nn elastic upper strap stitched to form a pair of loops, each of which receives an insulin bottle, and an elastic lower strap which holds a container of freezing material, such as "Blue Ice."
U.S. Pat. No. 4,573,581 to H. R. Galloway et al. discloses a container for protecting medications in the form of tablets from heat and light. The container is internally insulated by a multi-layer reflecting shield including two aluminum foil layers and an expanded polystyrene layer. A tube containing the tablets is surrounded by a heat sink made from a synthetic resin which does not absorb the vapor phase of the contained medication.
U.S. Pat. No. 4,738,364 to S. Yeager discloses a portable medicine protector including a hollow walled container having a cavity filled with a suitable liquid (e.g., water or Blue Ice) which may be frozen in a household freezer. A depression or cavity formed in the container receives medicine such as bottles of liquid. To inhibit freezing of the medicine, the bottom and sides of the cavity have ribbed members which prevent direct contact between a medicine bottle and the side walls of the container.
U.S. Pat. No. 4,955,480 to W. C. Sexton discloses an insulated carrier for-transporting insulin or other medications subject to rapid deterioration or degradation when exposed to ambient temperature conditions. The carrier includes a central block of expanded polystyrene foam, shaped as a rectangular parallelepiped, which has a cylindrical vertical bore. A polystyrene lid is hingedly attached to the block top and a polystyrene base block is secured to the base bottom. A vial of medication is inserted into a plastic vial with a removable lid which is inserted into the bore. The plastic vial rests on a hollow ball which contains a refreezable liquid, such as water, or a degraded collagen matrix containing thermal and chemical stabilizers.
U.S. Pat. No. 5,390,791 to S. Yeager discloses a portable medicine carrier for transporting medications stored in vials. The carrier is filled with a liquid that freezes at a temperature that is approximately equal to the desired storage temperature of the medication. Formed in the top surface of the carrier is a cavity which accepts vials of medication. Within the cavity are compartments of various sizes so as to accommodate a variety of vial shapes and sizes. The carrier is placed in a freezer to allow the liquid to freeze. The vials are then placed within appropriate compartments. The side walls of the cavity include ribbed members transverse to the width of the carrier which prevent vials from contacting the side walls.
Although these references address the need for a portable medication carrier, none provides means to monitor and display the temperature within the carrier, so that a user can be assured that the medication has remained sufficiently cold and also be apprised in time to take appropriate measures should the temperature exceed the acceptable limit.